545 research outputs found
Alpha decay and proton-neutron correlations
We study the influence of proton-neutron (p-n) correlations on alpha-decay
width. It is shown from the analysis of alpha Q values that the p-n
correlations increase the penetration of the alpha particle through the Coulomb
barrier in the treatment following Gamow's formalism, and enlarges the total
alpha-decay width significantly.
In particular, the isoscalar p-n interactions play an essential role in
enlarging the alpha-decay width.
The so-called "alpha-condensate" in Z > 84 isotopes are related to the strong
p-n correlations.Comment: 5 pages, 6 figures, accepted for publication in Phys. Rev. C (R.C.
Recommended from our members
Minutes of the fifth annual meeting of the panel on reference nuclear data
The minutes include: approval of agenda and minutes of the fourth meeting; elections; reactor physics data needs; fusion data needs; biomedical data needs; status of international and national cooperation; status and availability of data files; status of transfer of responsibilities from NDP to NNDC; status of publications; on-line data base systems; and summary of recommendations and actions. (GHT
Simplified amino acid alphabets based on deviation of conditional probability from random background
The primitive data for deducing the Miyazawa-Jernigan contact energy or
BLOSUM score matrix consists of pair frequency counts. Each amino acid
corresponds to a conditional probability distribution. Based on the deviation
of such conditional probability from random background, a scheme for reduction
of amino acid alphabet is proposed. It is observed that evident discrepancy
exists between reduced alphabets obtained from raw data of the
Miyazawa-Jernigan's and BLOSUM's residue pair counts. Taking homologous
sequence database SCOP40 as a test set, we detect homology with the obtained
coarse-grained substitution matrices. It is verified that the reduced alphabets
obtained well preserve information contained in the original 20-letter
alphabet.Comment: 9 pages,3figure
Roles of proton-neutron interactions in alpha-like four-nucleon correlations
An extended pairing plus QQ force model, which has been shown to successfully
explain the nuclear binding energy and related quantities such as the symmetry
energy, is applied to study the alpha-like four-nucleon correlations in
1f_{7/2} shell nuclei.
The double difference of binding energies, which displays a characteristic
behavior at , is interpreted in terms of the alpha-like
correlations. Important roles of proton-neutron interactions forming the
alpha-like correlated structure are discussed.Comment: 10 pages, 2 figures, RevTex, submitted to Phys. Rev.
Testing the Meson Cloud Model in Inclusive Meson Production
We have applied the Meson Cloud Model to calculate inclusive momentum spectra
of pions and kaons produced in high energy proton-proton and proton-nucleus
collisions. For the first time these data are used to constrain the cloud
cut-off parameters. We show that it is possible to obtain a reasonable
description of data, especially the large () part of the
spectrum and at the same time describe (partially) the E866 data on and . We also discuss the relative strength of the
and vertices. We find out that the corresponding cut-off
parameters should be both soft and should not differ by more than 200 MeV from
each other. An additional source (other than the meson cloud) of sea antiquark
asymmetry, seems to be necessary to completely explain the data. A first
extension of the MCM to proton nucleus collisions is discussed.Comment: 14 pages, Latex, 6 ps figures. Submitted to Phys. Rev.
Changes in Physician Knowledge, Attitudes, Beliefs, and Practices regarding Lung Cancer Screening
More patients die of lung cancer than breast, colorectal, and prostate cancers combined (1). After the National Lung Screening Trial finding of a 20% relative reduction in mortality of lung cancer with lung cancer screening (LCS) by low-dose computed tomography (LDCT) (2), the U.S. Preventive Services Task Force published recommendations for LCS in high-risk patients (current and former heavy smokers aged 55–80 yr) annually with LDCT (3)
Systematics of Leading Particle Production
Using a QCD inspired model developed by our group for particle production,
the Interacting Gluon Model (IGM), we have made a systematic analysis of all
available data on leading particle spectra. These data include diffractive
collisions and photoproduction at HERA. With a small number of parameters
(essentially only the non-perturbative gluon-gluon cross section and the
fraction of diffractive events) good agreement with data is found. We show that
the difference between pion and proton leading spectra is due to their
different gluon distributions. We predict a universality in the diffractive
leading particle spectra in the large momentum region, which turns out to be
independent of the incident energy and of the projectile type.Comment: 13 pages, Latex, 4 ps figures. To appear in Phys. Rev.
Opinions and Practices of Lung Cancer Screening by Physician Specialty
BACKGROUND In response to the National Lung Screening Trial, numerous professional organizations published guidelines recommending annual lung cancer screening with low-dose computed tomography (LDCT) for high-risk patients. Prior studies found that physician attitudes and knowledge about lung cancer screening directly impacts the number of screening exams ordered.METHODS In 2015, we surveyed 34 pulmonologists and 186 primary care providers (PCPs) to evaluate opinions and practices of lung cancer screening in a large academic medical center. We compared PCP and pulmonologist responses using t-tests and χ2 tests.RESULTS The overall survey response rate was 40% (39% for PCPs and 50% for pulmonologists). Pulmonologists were more likely than PCPs to report lung cancer screening as beneficial for patients (88.2% versus 37.7%, P < .0001) and as being cost-effective (47.1% versus 14.3%, P = .02). More pulmonologists (76%) reported ordering a LDCT for screening in the past 12 months compared to PCPs (41%, P = .012). Pulmonologists and PCPs reported similar barriers to referring patients for lung cancer screening, including patient costs (82.4% versus 77.8%), potential for emotional harm (58.8% versus 58.3%), high false positive rate (47.1% versus 69.4%), and likelihood for medical complications (47.1% versus 59.7%).LIMITATIONS Our results are generalizable to academic medical centers and responses may be susceptible to recall bias, non-response bias, and social desirability bias.CONCLUSION We found significant differences in opinions and practices between PCPs and pulmonologists regarding lung cancer screening referrals and perceived benefits. As lung cancer screening continues to emerge in clinical practice, it is important to understand these differences across provider specialty to ensure screening is implemented and offered to patients appropriately
Opinions, practice patterns, and perceived barriers to lung cancer screening among attending and resident primary care physicians
Introduction: The US Preventive Services Task Force recommended annual lung cancer screening with low-dose computed tomography (LDCT) for high-risk patients in December 2013. We compared lung cancer screening-related opinions and practices among attending and resident primary care physicians (PCPs). Methods: In 2015, we conducted a 23-item survey among physicians at a large academic medical center. We surveyed 100 resident PCPs (30% response rate) and 86 attending PCPs (49% response rate) in Family Medicine and Internal Medicine. The questions focused on physicians’ opinions, knowledge of recommendations, self-reported practice patterns, and barriers to lung cancer screening. In 2015 and 2016, we compared responses among attending versus resident PCPs using chi-square/Fisher’s exact tests and 2-samples t-tests. Results: Compared with resident PCPs, attending PCPs were older (mean age =47 vs 30 years) and more likely to be male (54% vs 37%). Over half of both groups concurred that inconsistent recommendations make deciding whether or not to screen difficult. A substantial proportion in both groups indicated that they were undecided about the benefit of lung cancer screening for patients (43% attending PCPs and 55% resident PCPs). The majority of attending and resident PCPs agreed that barriers to screening included limited time during patient visits (62% and 78%, respectively), cost to patients (74% and 83%, respectively), potential for complications (53% and 70%, respectively), and a high false-positive rate (67% and 73%, respectively). Conclusion: There was no evidence to suggest that attending and resident PCPs had differing opinions about lung cancer screening. For population-based implementation of lung cancer screening, physicians and trainees will need resources and time to address the benefits and harms with their patients
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